U.S. patent application number 14/095523 was filed with the patent office on 2014-04-03 for semi-automated ophthalmic photocoagulation method and apparatus.
This patent application is currently assigned to TOCON MEDICAL LASER SYSTEMS, INC.. The applicant listed for this patent is TOCON MEDICAL LASER SYSTEMS, INC.. Invention is credited to Steven Thomas Charles.
Application Number | 20140094784 14/095523 |
Document ID | / |
Family ID | 40523915 |
Filed Date | 2014-04-03 |
United States Patent
Application |
20140094784 |
Kind Code |
A1 |
Charles; Steven Thomas |
April 3, 2014 |
SEMI-AUTOMATED OPHTHALMIC PHOTOCOAGULATION METHOD AND APPARATUS
Abstract
An ophthalmic treatment system of an embodiment is used for
performing therapy on target tissue in a patient's eye. The
ophthalmic treatment system comprises, a light source, a delivery
system, an obtaining means, a setting means and control
electronics. The light source is configured to produce treatment
light. The delivery system is configured to deliver the treatment
light to the patient's eye. The obtaining means is configured to
obtain information acquired by capturing the patient's eye. The
setting means is used for setting a position in the patient's eye
by using the information obtained by the obtaining means. The
control electronics is configured to control the delivery system
based on the position set by the setting means.
Inventors: |
Charles; Steven Thomas;
(Memphis, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOCON MEDICAL LASER SYSTEMS, INC. |
Santa Clara |
CA |
US |
|
|
Assignee: |
TOCON MEDICAL LASER SYSTEMS,
INC.
Santa Clara
CA
|
Family ID: |
40523915 |
Appl. No.: |
14/095523 |
Filed: |
December 3, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11868387 |
Oct 5, 2007 |
|
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14095523 |
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Current U.S.
Class: |
606/4 |
Current CPC
Class: |
A61F 9/00821 20130101;
A61B 3/102 20130101; A61F 2009/00878 20130101; A61B 3/135 20130101;
A61F 2009/00863 20130101; A61F 2009/00846 20130101; A61F 2009/00897
20130101; A61F 9/0079 20130101; A61F 9/008 20130101; A61F 9/00823
20130101; A61F 2009/00851 20130101 |
Class at
Publication: |
606/4 |
International
Class: |
A61F 9/008 20060101
A61F009/008 |
Claims
1. An ophthalmic treatment system for performing therapy on target
tissue in a patient's eye, comprising: a light source configured to
produce treatment light; a delivery system configured to deliver
the treatment light to the patient's eye; an obtaining means
configured to obtain information acquired by capturing the
patient's eye; a setting means that is used for setting a position
in the patient's eye by using the information obtained by the
obtaining means; and control electronics configured to control the
delivery system based on the position set by the setting means.
2. The ophthalmic treatment system of claim 1, wherein the setting
means is used for setting a position for the treatment light to be
irradiated, and the control electronics control the delivery system
so that the treatment light is irradiated to this position.
3. The ophthalmic treatment system of claim 2, wherein the setting
means is used for marking around the position at which the
treatment light is to be irradiated.
4. The ophthalmic treatment system of claim 1, wherein the setting
means is used for setting a position at which irradiation of the
treatment light is to be avoided, and the control electronics
control the delivery system so that the treatment light is not
irradiated to this position.
5. The ophthalmic treatment system of claim 4, wherein the setting
means is used for marking around the position at which the
irradiation of the treatment light is to be avoided.
6. The ophthalmic treatment system of claim 1, wherein the
information obtained by the obtaining means includes an image
acquired by an OCT system, SLO, fundus camera or slit lamp
microscope, or a 2-dimansional or 3-dimensional map based on this
image.
7. The ophthalmic treatment system of claim 6, wherein the setting
means is used for setting a position in the image or the map
obtained by the obtaining means.
8. The ophthalmic treatment system of claim 1, further comprising a
camera configured to capture the patient's eye.
9. The ophthalmic treatment system of claim 8, wherein the camera
captures a live image of the patient's eye.
10. The ophthalmic treatment system of claim 8, further comprising
a display device that is used for displaying the image captured by
the camera.
11. The ophthalmic treatment system of claim 10, wherein the
display device displays the information obtained by the obtaining
means together with the image captured by the camera.
12. The ophthalmic treatment system of claim 8, further comprising
a storage device configured to store the image captured by the
camera.
13. The ophthalmic treatment system of claim 1, further comprising
a camera configured to capture a live image of the patient's eye,
wherein the information obtained by the obtaining means includes an
image acquired by an OCT system, SLO, fundus camera or slit lamp
microscope, and/or a 2-dimansional or 3-dimensional map based on
this image, and the control electronics carries out processing for
registering the image and/or the map to the live image.
Description
RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 11/868,387 filed on Oct. 5, 2007, which is incorporated
herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention pertains generally to the ophthalmic
treatment of a patient's eye, and more particularly to a machine
and method for semi-automated ophthalmic photomedical treatment of
a patient's eye.
BACKGROUND OF THE INVENTION
[0003] Presently, conditions such as diabetic retinopathy, vein
occlusion and age-related macular degeneration have been treated
with photocoagulation induced by visible laser light. While this
type of visible laser light treatment may halt the progress of the
underlying disease, it can be problematic.
[0004] One problem is that some ophthalmic treatments require the
application of a large number of laser doses to the retina, which
can be tedious and time consuming. Such treatments call for the
application of each dose in the form of a laser beam spot applied
to the target tissue for a predetermined amount of time. The
physician is responsible for ensuring that each laser beam spot is
properly positioned on the intended target tissue as well as away
from sensitive areas of the eye such as the macula that could
result in permanent unintended damage. Since some treatments can
require hundreds of laser beam spots to treat the target tissues,
the overall treatment time can be quite long and require great
physician skill to ensure a precise and adequate treatment of the
entire target tissue area is accomplished.
[0005] To reduce the treatment time needed for retinal
photocoagulation, a system and method has been proposed for
applying multiple laser spots automatically in the form of a
treatment pattern of spots, so that an area of target tissue is
efficiently treated by multiple spots pre-positioned on the tissue
in the form of the pattern. See for example U.S. Patent
Publications 2005/0286019, 2006/0100677 and 2007/0129775. However,
rapid delivery of multiple beam spots in patterns raises new
issues. For example, the exposure time is limited because of
possible eye movement, and even with short exposure times there can
be patient eye movement at the moment the physician triggers the
application of the treatment pattern that could result in the
application of the treatment pattern to non-targeted tissue.
Moreover, physicians typically identify the tissue locations to be
targeted using pre-treatment images of the eye. Present systems and
techniques for applying patterns of spots have no capability of
ensuring the tissue targeted for treatment by the physician is the
same as that identified in the pre-treatment images. Thus, the
physician is solely responsible for ensuring the tissue about to be
treated is the same tissue identified in the pre-treatment images,
and that the stability of the eye position will allow an accurate
application of the treatment pattern. Rapid eye movements called
saccades cannot be adequately tracked or compensated for by
physicians. Typical physician latency times are approximately 400
ms, and thus physicians usually can only move the laser aiming
device at a 5 Hz rate (while eye movements are approximately 100
times faster). Anesthetizing eye muscles using an injection of an
anesthetic agent behind the eye can stabilize the eye but carries a
risk of perforating the eye, the optic nerve or the blood vessels,
is quite painful, and could even cause death.
[0006] Accordingly, there is a need for a semi-automated ophthalmic
laser treatment and method that compensates for patient eye
movement, and/or can assist the physician in verifying and
adjusting alignment of the treatment pattern to the target tissue
identified in pre-treatment images of the eye.
SUMMARY OF THE INVENTION
[0007] An embodiment solves the aforementioned problems by
providing an ophthalmic treatment system for performing therapy on
target tissue in a patient's eye, comprising: a light source
configured to produce treatment light; a delivery system configured
to deliver the treatment light to the patient's eye; an obtaining
means configured to obtain information acquired by capturing the
patient's eye; a setting means that is used for setting a position
in the patient's eye by using the information obtained by the
obtaining means; and control electronics configured to control the
delivery system based on the position set by the setting means.
[0008] Other objects and features of the present invention will
become apparent by a review of the specification, claims and
appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic diagram illustrating a light
generation and scanner system for semi-automated ophthalmic
treatment.
[0010] FIGS. 2A-2D illustrate exemplary scan patterns for use with
a pulsed or gated light source.
[0011] FIGS. 3A-3D illustrate exemplary scan patterns for use with
a continuous wave (CW) light source.
[0012] FIG. 4 is a flow diagram illustrating a method of
semi-automated ophthalmic treatment.
[0013] FIG. 5 is a schematic diagram illustrating an alternate
embodiment of a light generation and scanner system for
semi-automated ophthalmic treatment.
[0014] FIG. 6 is a schematic diagram illustrating a second
alternate embodiment of a light generation and scanner system for
semi-automated ophthalmic treatment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] A system and method for semi-automated, doctor-in-the-loop,
ophthalmic treatment of target eye tissue is disclosed which
accurately identifies tissue areas for treatment, aligns a light
delivery system to those tissue areas for treatment, and adjusts
alignment to compensate for patient eye movement during
treatment.
Pattern Generation System
[0016] FIG. 1 is a schematic diagram of a system 10 suitable for
performing semi-automated ophthalmic treatment of a patient's eye
tissue. Alignment light (for an aiming beam or alignment pattern)
is created using an alignment light source 20, which may be
controlled by control electronics 22 via an input/output device 24.
It should be noted that the use of alignment light is optional, and
therefore elements for its generation and use could be omitted.
Therapeutic light is created using a therapeutic light source 26.
Light sources 20 and 26 can be any gas or solid state laser device,
or even one or more light emitting diodes. Light sources 20/26 are
preferably separate devices because they typically will produce
light at different wavelengths and power levels. However, they
could be combined into a single light source that produces
alignment and therapeutic light with differing or identical
wavelengths. Alignment light from source 20 preferably is visible
to the eye (however, if an alternate visualization scheme such as
infrared imaging is employed, it may be non-visible). Therapeutic
light from source 26 may also be visible, but need not be. If
therapeutic light source 26 does produce visible light, it may be
also used for producing the alignment light instead of alignment
light source 20 (e.g. by simply reducing its output power during
system alignment when no eye safety filters are in the
visualization pathway). Likewise, if therapeutic light source 26
produces non-visible light, it may be used for alignment in a
similar manner with a non-visible imaging scheme (e.g. by using an
infrared imaging device).
[0017] Light output from therapeutic light source 26 first
encounters a mirror 30 which reflects a fixed portion of the
therapeutic light to a photodiode 32 to measure its power for
safety and real time power adjustment purposes. The therapeutic
light then encounters shutter 34, mirror 36, and mirror 38. Shutter
34 fundamentally serves to control the delivery of the therapeutic
light, and can be used to rapidly gate and/or generally block the
therapeutic light. Mirror 36 is an optional turning mirror, and
mirror 38 is used to combine the therapeutic light with the
alignment light from light source 20 to form combined
alignment/therapeutic light beam 46, where alignment light from
source 20 may be adjusted so that it is coincident with the
therapeutic light downstream. It should be noted that the alignment
light and the therapeutic light would typically not be produced
simultaneously, and in that case mirror 36 in actuality combines
beam paths for these two beams of light (i.e. alignment/therapeutic
light 46 contains only alignment light at certain times and
therapeutic light at other times). A mirror 40 is used to reflect a
portion of the combined alignment and therapeutic light into
photodiode 42 for additional measurement (and also provides
redundant monitoring of the state of shutter 34).
[0018] A lens 44 can be used to focus the combined
alignment/therapeutic light 46 prior to its entry into a scanner
assembly 48. Lens 44 may be a single lens, or a compound lens. If
lens 44 is a compound lens, it may be configured as a zoom lens
assembly that adjusts the size of spots S, and therefore, pattern
P. Another lens 50 can be placed one focal length away from the
optical midpoint of the scanner assembly 48 to produce a
telecentric scan (however this is optional). For systems including
lens 50, a telecentric scan serves to maximize the scan speed, so
long as the remaining optical elements are large enough to contain
the entire scan. Most of the current available optical treatment
contact lenses demand telecentric input.
[0019] Scanning assembly 48 preferably includes two optical
elements 56 and 58 (e.g. mirrors, lenses, diffractive elements,
rotating wedges, etc.), that can be individually tilted or moved in
an orthogonal manner to deviate (deflect) the optical beam 46, and
ultimately direct it towards the target tissue in the form of a
pattern P (such as those shown in FIGS. 2A-2D and 3a-3D, and
described in further detail below). For example, optical elements
56/58 can be mirrors mounted to galvanometers, solenoids,
piezoelectric actuators, motors, servos, motors or other type of
actuators for deflecting the beam 46 by tilting the mirrors. Of
course, single element 2-dimensional scanners may also be used,
such as acousto-optic deflectors, optical phased arrays, or micro
mirror devices. Alternately, the mirrors could have optical power
(e.g. have surface curvature), where deflecting the beam can be
accomplished by translating the mirrors. Or, optical elements 56/58
could be one or more lenses, which deflect the beam by
translational movement of the lenses.
[0020] Light 46 next encounters mirror 52, which reflects the light
toward the target tissue in the patient's eye 1. Mirror 52 includes
a high reflective coating that spectrally matches the outputs of
the alignment and therapeutic light, yet allows visualization light
coming from the target to pass through so that target area can be
visualized through mirror 52. Preferably, the coating would be
constructed to white balance the transmission through mirror 52,
where the coating is more complicated and makes the colors appear
more natural instead of a pinkish result when using a green notch
filter coating. Lens 50 may also be used to image the optical
midpoint of the scanner assembly 48 onto mirror 52, to minimize the
size of the mirror 52 in an attempt to increase the overall solid
angle subtended by the visualization device. When mirror 52 is
small, it may be placed directly in the visualization path without
much disturbance. Mirror 52 may also be placed in the center of a
binocular imaging apparatus, such as a Zeiss slitlamp
biomicroscope, without disturbing the visualization.
[0021] An optional ophthalmic lens 60 may be placed directly before
the eye to aid in visualization, such as might be done with any
ophthalmoscope, slit lamp biomicroscope, fundus camera, SLO, or OCT
system. Ophthalmic lens 60 may be a contact or non-contact lens,
and may also be used in conjunction with lens 50 to provide for
conjugate pupil planes such that the scanning pivots about the
patient's iris, thus maximizing the system's retinal scan field.
Visualization of the target tissue is preferably accomplished by
directly viewing the retina through mirror 52 by the physician
(e.g. using a slitlamp biomicroscope) as well as using a high frame
rate camera 62 (e.g. CCD or CMOS camera) to create an electronic
image from the light passing through mirror 52. The electronic
image can be stored by the system, displayed on a graphical user
interface (GUI) 54, and used by the control electronics 22 to
confirm/adjust alignment as described below.
[0022] The mirrors, lenses and other optical elements between the
light sources 20/26 and the patient's eye 1 form a delivery system
68 that can be controlled to deliver the alignment/treatment
patterns to the intended target tissue. More specifically, scanner
48, under the control the control electronics 22, creates the
alignment and treatment patterns P of the alignment and therapeutic
light respectively, as discussed in further detail below with
respect to FIGS. 2A-2D and 3A-3D. Any other components of delivery
system 68 can be movably controlled by control electronics 22, and
thus affect the final alignment of delivery system 68. The position
and character of pattern P may be manually controlled by the
physician adjusting the position of lens 60, as well as
electronically controlled by commands or controls input via a
graphic user interface (GUI) 54 and/or automated control by the
control electronics 22 as described below. GUI 54 can be a single
touch screen for displaying system options, entering commands, and
viewing images from camera 62 as well as imported images.
Alternately, GUI 54 can comprise several separate components,
including a keypad or keyboard for entering commands, a touch
sensitive screen for viewing system options and entering system
commands, and/or a stand alone visual display screen for viewing
images from camera 62 (as well as viewing pre-treatment images and
treatment templates described in more detail below). Pattern P, or
any of its elements, may also be made to be perceived by the
physician as blinking.
Alignment/Treatment Patterns
[0023] The alignment and treatment patterns generated by system 10
may be comprised of a single spot of light, multiple spots of
light, a continuous pattern of light, multiple continuous patterns
of light, and/or any combination of these, utilizing either or both
continuous wave (CW) and pulsed light sources, for standard,
selective, and/or sub-threshold therapies (i.e. therapies that do
not result in any visible signs of treatment). In addition, the
alignment pattern need not be identical to the treatment pattern,
but preferably defines its location (e.g. its boundaries or its
center, etc.) in order to assure that the therapeutic light is
delivered only within the desired target area or at a location
centered at a particular location. This may be done, for example,
by having the alignment pattern provide an outline of the intended
treatment pattern, or a point or cross-hairs showing a center
position. This way, the spatial extent or center point of the
treatment pattern may be made known to the physician, if not the
exact locations of the individual spots themselves, and the
scanning thus optimized for speed, efficiency and accuracy.
[0024] The alignment and treatment patterns are preferably formed
as a pattern P of spots S of light projected onto the target
tissue, as illustrated in FIGS. 2A-2D. Spots S are shown as round,
but need not be. FIGS. 3A-3D illustrate how one or more spots S can
be used to trace out or even form elongated straight or curved line
segments to form patterns P, which is ideal for continuous wave
(CW) light sources. For example, in FIG. 3A, spot S is scanned at a
velocity V to form line segment scans LS of pattern P. Each line
segment LS terminates when the light source is no longer delivering
light to the spot S being scanned that forms the line segment LS.
This may be done in many ways, such as, gating the light source
on-and-off directly, using a shutter placed in the optical path, by
use of an aperture, etc. As shown in FIG. 3B, a pattern P may be
formed of a plurality of line segments LS and/or spots S. The line
segment LS may be shaped or curved, as illustrated in FIG. 3C, or
even curved/shaped to form geometric objects or symbols as
illustrated in FIG. 3D (which is particularly suited as an outline
of the target tissue for the alignment pattern as previously
discussed).
[0025] Thus, for the purposes of this disclosure, a "pattern" of
light shall mean at least two spots S that do not completely
overlap (or do not overlap at all), or one or more spots that move
during a single pulse or with CW light resulting in a projected
straight or curved line segment. Additionally, the alignment
pattern need not be identical to the treatment pattern. For
example, if a treatment pattern contains hundreds of spots, its
location can be identified by less complicated indicia (e.g.
alignment pattern of just a few spots showing boundaries and/or the
center of the treatment pattern). In fact, a single stationary
alignment beam spot showing the center of the treatment pattern
could be used. Simplified alignment patterns, or use of a single
stationary alignment beam spot, can be projected more simply and
quickly than trying to replicate the entire treatment pattern with
the alignment light.
Semi-Automated Alignment Confirmation and Compensation
[0026] Typically, physicians use one or more pre-treatment images
and/or two dimensional or three dimensional data sets of the
patient's eye (images of the eye often taken well before the
treatment--sometimes earlier by days and at a different clinical
location using different equipment) to identify the precise
locations of tissue to be targeted for treatment. During
conventional treatment procedures, the physician must manually
identify and target the patient's eye tissue that was previously
identified using the pre-treatment images. If there is any mismatch
between the tissue locations previously identified in the
pre-treatment images and those targeted during treatment, then
healthy tissue will end up being treated and intended target tissue
will escape treatment. Therefore, to better compliment the
physician's alignment of treatment pattern to the intended target
tissue, the system 10 uses one or more pre-treatment images to
produce a treatment template which is registered to a live image of
the patient's eye to verify alignment, compensate for patient eye
movement, and/or control varying dosages of treatment light even
within the same treatment pattern.
[0027] FIG. 4 illustrates the method of semi-automated alignment
confirmation and compensation. In step 1, a pre-treatment image of
the eye is generated. While the following discussion refers to a
single pre-treatment image for simplicity, multiple pre-treatment
images of the same or different type can be generated as well.
Image generation can be performed immediately before treatment at
the treatment site, or at a different location long before
treatment. Sources of the pre-treatment image can include a digital
color fundus camera image, a fundus camera angiogram, a confocal
angiogram, a wide-field angiogram (recent emphasis on peripheral
ischemia in diabetic retinopathy), an indocyanine green angiogram,
an auto-fluorescence image, a monochromatic image, an infrared
image, a spectral domain or time domain 3D OCT (ocular coherence
tomography) with point-to-point registration to fundus (retinal)
image, a multi-focal ERG, a preferential hyperacuity perimetry, or
a static perimetry data set. The data forming the pre-treatment
image can be 2D or 3D mapped functional data, OCT data, etc. The
image can also be a composite image using multiple different
sources of 2D data and images from the patient's eye.
[0028] In step 2, a treatment template is created which identifies
what portion(s) of the tissue in the pre-treatment image should be
treated. The treatment template is preferably constructed using an
electronic computing device with a visual display and user inputs
such as a joystick, mouse or other pointing device. This computing
device could be separate from the treatment system, or can be
integral to the treatment system. For example, the treatment
template can be formed by loading the pre-treatment image into a
conventional computer, and then digitally marking locations in that
image which warrant treatment using the computer's display screen
and conventional computer input devices (keyboard, mouse, joystick,
touchscreen, etc.). Alternately, the pre-treatment image can be
loaded into system 10 using an input port 66, where the computing
device includes control electronics 22. The treatment template can
then be generated using the GUI 54 and possibly one or more input
devices 64.
[0029] Preferably, the computing device for creating the treatment
template includes software or hardware tools for aiding the
physician in marking locations on the image of the patient's eye
for treatment. For example, the computing device can include tools
for adding or subtracting spots from a treatment pattern, or allow
the physician to outline an area for treatment in which a treatment
pattern is added. Ideally the computing device will aid the
physician in determining one or more treatment patterns for which
the system 10 described above is capable of producing. The
computing device could provide a library of sample treatment
patterns of adjustable size and shape, to allow the physician to
select, locate and adjust one or more treatment patterns to cover
entire areas of the image for which treatment is warranted. Typical
patterns could include but are not be limited to: initial or
fill-in pan retinal photocoagulation (PRP), grid treatment pattern,
sector treatment pattern, patterns that "paint" a choroidal
neovascular membrane, patterns that "paint" around a retinal hole
or tear, or patterns that "paint" around automatically identified
areas for treatment of microaneurysms, patterns required by a
clinical trial, and/or custom patterns developed by an expert or
frequent user. In developing treatment patterns, the computing
device can be configured to automatically build treatment patterns
that avoid certain areas of the image. For example, the computing
device can be set to locate and avoid shapes or areas that are
black (indicating previous treatment) or red (indicating large
vessels or blood), or avoid physician designated areas such as the
fovea and optic nerve. The computing device can also be configured
to locate and target areas that are likely targets, such as a
choroidal neovascular membrane, microaneurysms, or a central serous
retinopathy leak. Spot size could vary by location. PRP spots could
be larger in the periphery and smaller near the posterior pole, and
could be evenly interspersed between previous spots determined by
the black avoidance algorithm described above or a registered
template from a previous treatment session.
[0030] Treatment template generation need not be limited to
identifying and controlling just treatment locations. Dosage
control information can also be embedded into the treatment
template, and used by the system 10 to automatically vary the
dosage (power, spot size and duration) of treatment light for
various locations within the targeted tissue. This can be an
automated function performed by the computing device, or manually
performed by the physician, or a combination of the both. For
example, laser energy absorption is generally a function of
pigmentation. Tissues that are lighter in color or are more
reflective will generally require a higher dosage of treatment
light. In contrast, tissues that are dark are more absorptive, and
will generally require a lower dosage of treatment light. In
generating the treatment template, pigmentation and
reflectance/absorption characteristics can be used by the computing
device and/or the physician to determine the proper dosage for each
spot or location within the targeted tissue. By including this
information in the treatment template, the system 10 can then use
this information to automatically adjust the laser power, and/or
dwell time to provide the optimal treatment dosage at each location
within the targeted tissue (even on a real time spot-by-spot basis
for a treatment pattern containing hundreds of spots). Although the
absorption measurement would be optimal if determined at a
wavelength near the intended treatment wavelength, melanin is a
broadband absorber, and rod and cone pigments are also cumulatively
green absorbers (near the most widely used treatment wavelengths),
which means that imaging at the exact treatment wavelength may not
be needed for many procedures employing automated dosage control.
Automated dosage control will result in producing greater accuracy
and safety, enabling more precise sub-threshold treatment and
reducing the likelihood of Bruch's membrane rupture and
bleeding.
[0031] The treatment template represents a digital overlay for the
pre-treatment image that defines locations and dosages of
treatment, including the precise treatment pattern(s) and dosages
within such treatment pattern(s). The treatment template can be
incorporated into the same digital file containing the
pre-treatment image, or typically stored as a separate digital
file. Using a treatment template allows the physician to take his
or her time to precisely define exactly where treatment spots or
patterns will be applied, and at what dosages, by careful analysis
of the pre-treatment image outside of the patient's presence (and
possibly even outside of any clinical environment). The treatment
template can even be "digitally signed" by the physician and
indelibly archived for risk management purposes. The treatment
template can also serve as an operation report after treatment.
[0032] In step 3, the pre-treatment image and treatment template
are loaded into system 10 via input port 66, and preferably stored
in a storage device 22a (e.g. hard drive, flash non-volatile
memory, CD, DVD, etc.) that is contained within or connected to
control electronics 22. Input port 66 can be a port for receiving
electronic files from a storage device (i.e. CD/DVD disk, flash
memory key, etc.), or a network connection for receiving electronic
files over a network, or even provide a direct connection to the
computing device used to generate the treatment template. If the
system 10 is used to generate the treatment template, then this
loading step would be omitted, as the pre-treatment image data
would have been previously loaded into system 10, and the treatment
template would have been created internally by system 10.
[0033] In step 4, the delivery system 68 is aligned to the
patient's eye. This can be accomplished by the physician holding
and aligning the lens 60 (preferably a contact lens) to the
patient's eye (which solves image optimization, obliquity,
reflections from the contact lens, pupil size, pupil decentration,
corneal & lens opacities, and astigmatism problems), and/or by
manipulating the alignment of the delivery system 68 via one or
more input devices/controls 64 and/or GUI 54 while directly viewing
the target tissue or using the real-time image from camera 62 as a
guide. When the delivery system 68 is generally aligned to the
patient's eye, camera 62 will capture a live image of the patient's
eye, which is sent to control electronics 22 and displayed on GUI
54 or another display device.
[0034] In step 5, system 10 registers the pre-treatment image and
treatment template to the live image from camera 66, so that the
system 10 can precisely determine where on the pre-treatment image
and treatment template the delivery system is presently aimed to.
This image registration can be accomplished using affine transform
or other stretching or morphing algorithms which match the
two-dimensional video amplitudes of the live image from camera 62
to the two-dimensional video amplitudes of the pre-treatment image.
This process involves stretching or morphing the pre-treatment
image so as to create a best fit with the live image. Optionally,
feature recognition techniques can be used to perform the image
registration. As long as the alignment of the delivery system in
step 4 is close to the intended target tissue (i.e. so there is
substantial overlap between the pre-treatment and live images), the
system 10 will recognize the live image and register the
pre-treatment image to it.
[0035] Registration will likely not require megapixel images from
camera 62, where resolutions as low as 512.times.512 or VGA
(640/480) will likely prove to be sufficient (thus reducing cost
and enabling higher frame rates and lower processing bandwidth than
megapixel cameras). Camera 62 would typically include a
monochromatic sensor with high fill factor (100%) to improve photon
efficiency, or a progressively scanned sensor for better image
processing. Camera 62 can include infrared or visible sensing which
detects the retinal image from the white light illumination
commonly used by physicians to illuminate and visualize the target
tissue with the slitlamp biomicroscope. The frame rate of camera 62
should be significantly higher than video rates, as an unrestricted
eye requires approximately 1 kHz for stabilization of saccadic
movements. High viscosity coupling fluid and flanged lens contact
with high surface area can be used to somewhat decrease saccadic
velocities of the patient's eye.
[0036] It is desirable that the system maintain proper registration
in the event of patient eye movement, meaning that the system 10
would preferably detect and track eye movement while maintaining
registration. One non-limiting example of image registration that
can track eye movement is to use pipeline processing (preferably
using image processing on FPGA silicon such as done by Xilinix)
implementing Chi square algorithms (which have been shown to be
effective for retinal tracking) This process can be accomplished by
comparing the two-dimensional video amplitude of the current frame
of the live image of the patient's eye to that of the previous
frame, to determine the directionality and amplitude of any
movement. For example, the current frame image can be moved
iteratively, for example, one pixel to the right, where a
calculation is made to determine if there is a fit. This is
repeated with movements left, up and down, until the best fit or
match is achieved. Once the best fit is achieved, the amount of eye
movement can be determined by how many XY pixel movements were
needed to achieve the best fit/match. Those pixel movement
adjustments are then applied to the treatment template positioning
via movable mirrors to maintain proper registration with the live
image.
[0037] It is preferable that the physician confirm that proper
registration between the live camera image and the treatment
template (built on the pretreatment image) has been achieved. This
can be accomplished by using GUI 54, which can visually display an
overlay of the live image and the treatment template. This overlay
image will provide the visual confirmation the physician needs that
registration was performed properly, and the system is ready to
deliver the treatment pattern(s). Thus, while the system 10 locks
registration in automatically once the physician aligns the
delivery system 68 at or close to the intended targeted tissue, the
registration should be visually confirmed by the physician before
treatment begins.
[0038] Once registration is achieved, the overlaid visual display
of the live image and the pre-treatment image may indicate to the
physician that further manual alignment may be necessary to better
center the delivery system alignment to the target tissue as
defined by the treatment template. Misalignment may also be caused
by movement of the patient's eye. Thus, there may be additional
alignment of the delivery system 68 to the patient's eye by the
physician both during and after the image registration of step 5.
Alignment confirmation can be performed in several different ways.
The physician can manipulate delivery system alignment until the
target tissue defined by the treatment template is within view of
the display showing the image overlay, within a particular area on
the display, or even in the center of the display. Alternately, an
aiming beam can be directed to the eye that visually illustrates
the alignment of the delivery system, whereby the physician adjusts
alignment until the aiming beam is within (or even centered with
respect to) the treatment pattern defined by the treatment
template. Or, an alignment pattern as described above with respect
to FIG. 1 is projected onto the patient's eye, and the physician
adjusts delivery system alignment until the alignment pattern
partially or fully overlaps with, or is centered with respect to,
or even is perfectly aligned on a spot by spot basis to, the
treatment pattern as defined by the treatment template and
displayed on the image overlay display.
[0039] After registration has been confirmed, and any additional
alignment by the physician is completed so that the delivery system
68 is aligned at or near the proposed treatment area, the physician
activates treatment in step 6 by triggering an input device/control
64 (e.g. a foot pedal, a finger switch, or any other equivalent
trigger device), where the system 10 applies the treatment pattern
to the patient's eye. While the system could rely solely on the
physician's alignment (and simply be configured to prevent
treatment if the alignment is or becomes too misaligned relative to
the target tissue defined by the treatment template), it is
preferable that the system 10 actively manipulate alignment before
and during treatment to achieve and/or maintain alignment of the
delivery system 68 to the target tissue. More specifically, when
the physician triggers treatment, the system 10 confirms that
delivery system 68 is accurately aimed at the intended targeted
tissue (as defined by the treatment template). If it is not, the
system 10 (via control electronics 22) will search for the area
designated for treatment, and if found will adjust the alignment of
the delivery system 68 until it is aligned to that intended target
tissue (i.e. such that the treatment pattern will be projected onto
the eye tissue at the same locations and dosages as defined by the
treatment template). Moreover, as the treatment pattern is being
applied to the eye tissue, the alignment of the delivery system 68
will be constantly adjusted as needed to compensate for any eye
movement detected by the system (i.e. the system will track
real-time movements of the eye and make appropriate corrections to
the alignment of the delivery system 68). With this technique, the
physician need only align the delivery system 68 close to the
intended target tissue (course adjust), where the system 10 will
automatically complete and verify the alignment (fine adjust) using
the treatment template and then automatically apply the treatment
pattern to the eye tissue.
[0040] The true precision of the above described technique is
achieved by the physician creating a detailed template showing
exactly where treatment should occur and at what dosages, coupled
with a system that uses that template to achieve and maintain
alignment while applying the predetermined dosages of therapeutic
light to the target tissue. Precision is also achieved because it
is the actual tissue that is being treated (as opposed to the
pupil, iris, or another adjacent tissue) that is also being imaged
for alignment and dosage control. Moreover, because the system can
manipulate the delivery system alignment to track moving target
tissue, longer exposure times can be used to better project or
paint patterns or moving spots onto the target tissue for more
uniform treatment.
[0041] There are other advantages and uses for the treatment
templates described above. The treatment template from one
treatment session can be stored, and used later during a subsequent
treatment session as an accurate indicator of past treatment
locations. For example, in a PRP fill-in re-treatment, the
treatment template from an earlier treatment session can be used to
define and target tissue locations in-between previous laser
treatments. Generic treatment templates can also be generated for
widespread use among many candidate patients. For example,
ophthalmic experts can prepare treatment templates for specific
studies or optimized specialized treatment. These generic treatment
templates can be mapped to specific patient geometries with some
modifications, where the generic aspect of the intended treatment
is retained.
[0042] The search range within the pre-treatment image and
treatment template, and/or the amount of fine adjust applied to the
delivery system 68, is reduced by including the physician's course
alignment adjustment first, especially if the physician
continuously attempts to bring the target tissue into alignment
while the system corrects for eye movement as well. The above
described system and technique increase precision, safety, and
efficiency while reducing the risk of RPE creep caused by thermal
diffusion, thus allowing the physician to safely treat tissues
closer to sensitive areas such as the foveal avascular zone, the
macula, previous laser marks, etc.
[0043] There are many applications for the semi-automated treatment
system and technique described above, including treatment of
microaneurysms for diabetic macular edema (using small, bright red
dots as the identifier in the image), diabetic retinopathy and vein
occlusions, branch retinal vein occlusion (BRVO), central retinal
vein occlusion (CRVO), diabetic macular edema, focal extra-foveal
or peripapillary choroidal neovascular membranes (CNV), central
serous retinopathy (CSR) leaks, retinal angiomatous proliferation
(RAP) lesions, retinal breaks, teleangectasia, or feeder vessels
(typically identified by ICG, high frame rate angiography).
[0044] FIG. 5 shows a schematic diagram of an alternate embodiment
to the system of FIG. 1, with optical fiber delivery. In this
embodiment, lens 70 is used to inject the alignment and therapeutic
light 46 into an optical fiber 72. Light 46 exiting optical fiber
72 encounters lenses 74 and 76 which condition the light and can
act as a zoom system before the light enters the scanner assembly
48. An image of the output face of optical fiber 72 may be relayed
to the target area, and a "flat-top" intensity profile used, rather
than the Gaussian profile produced by gas lasers. The remainder of
the system of FIG. 5 is the same as that shown in FIG. 1.
[0045] FIG. 6 shows a schematic diagram of another embodiment which
is similar to that discussed above with respect to FIG. 1, but with
the addition of an adaptive optical element 92 in replacement of
scanning mirrors 56/58 in scanning assembly 48, for scanning the
light 46. In this embodiment, adaptive optical element 92 may be
reconfigured to produce a complex optical system. For example, both
a scan and any possible anamorphic correction maybe made to light
46 with this single element. Some examples of such an optical
element 92 include: deformable mirrors, deformable lenses, and
optical phase arrays. Scanner 48 could take other configurations as
well. Specifically, for significant eye movement, the scanner 48
can incorporate additional optics for additional degrees of
freedom, such as compensation for 5 degrees-of-freedom movement of
a retinal target with respect to the delivery system (3-D
translations, pitch, yaw). For example, if the eye rotates
significantly upward, pitch compensation up may not be sufficient,
whereas an optical system that can translate down and pitch up
while moving in with focus can be more versatile (possibly with the
aid of the physician). Other techniques of scanning light beam 46
could include the light sources as part of the scanner assembly 48
(i.e. beam movement by moving the light sources 20/34 themselves
directly), just using a single moving optical element elsewhere in
the delivery system (e.g. mirror 52), or manipulating any of the
other optical elements in the delivery system 68. If optical
elements 56/58 have optical power, then compensating optical
elements (not shown) may be added to produce an image, as opposed
to a simple illumination, on the target tissue.
[0046] It is to be understood that the present invention is not
limited to the embodiment(s) described above and illustrated
herein, but encompasses any and all variations falling within the
scope of the appended claims. For example, while the scanner 48 is
ideal for making the necessary (fine) alignment adjustments, other
optical elements in the delivery optical chain can be moved or used
to otherwise implement the fine position adjustment of the
treatment pattern before it is applied. Additionally, while lasers
are the preferred light sources for the treatment and/or alignment
light, any appropriate light sources can be utilized. It should be
noted that therapeutic light can be for diagnosis and/or treatment
purposes. While scanning assembly is described as forming both an
alignment pattern and a treatment pattern, it could simply pass
along an aiming beam from the alignment light source to visually
indicate a center or other position of the treatment pattern or a
simple treatment beam. The functionality of the control electronics
can be implemented entirely by one or more electrical components,
and/or include one or more components or modules found in software
and/or firmware.
* * * * *